How to Fit a Central Heating Radiator

Central heating for most is an essential way to keep the home warm and cozy. Replacing old radiators is not a difficult job providing you prepare and tackle the job in a logical way.

In this guide we provide step-by-step instructions that will help you install new central heating radiators properly without causing a mess or flooding your rooms.

Step 1

The first thing you need to do is to turn off the central heating system. Locate the switch in the heating cupboard, which is where your hot water cylinder will be fitted and turn it off.

Now turn off the stop cocks for the hot and cold water. Finally you need to drain the system. For this you’ll need to locate the drain-off point and attach a hose that is long enough to be trailed outside.

NOTE: Draining the system is necessary if you are going to be changing more than one radiator as this will prevent any of your floors being flooded. However, if you are changing a single radiator then repeat the first part, that is turn off the water and heating system and then close the valves on either end of the radiator.

There are TWO values, the first feeds hot water into the system while the other controls the heat by restricting the amount of hot water that fills the radiator.

IMPORTANT – before you do anything, make sure the heating is turned off and that the system is COLD. This job is better done in the summer time as you’ll be without heating until you have replaced the number of radiators you want.

Step 2

Once you have completed Step 1 you need to bleed each of the radiators. You should have a radiator key, that fits the square nut that is located at the top end of the radiator.

If you do not have this key then you can buy one from any DIY Store. Place the key on the nut and turn anti-clockwise. You will now hear air rushing out of the system and this is what you want.

Make sure you have a cloth handy because as the water in the radiator pushes the air completely out then water will start to come out. Once water comes out lock the nut by turning it in a clockwise direction. You need to repeat this for every radiator.

Step 3

Before removing the radiator check that both end valves are turned to the off position. Once you have done this you can unscrew the nuts, both ends, that connect the in and out flow pipes to the radiator. Have a small basin handy as a small amount of water may still be present at the ends of the pipes.

WARNING - If you did not drain the system then remember that the radiator is still FULL of water and the chances are this wall is going to be black and will stink, so you will need a basin to catch the water until you can place your hand over the ends to block it.

You can, if you like, attach a hose pipe and drain off the water or alternatively get a friend to help you – you both need to cover the ends so that the water does not flood the floor. While holding the ends, lift the radiator off the wall brackets and then tip the radiator at an angle over a very large bucket and drain it.

Remember a radiator full of water is very heavy and may require more than one large bucket – it is sometimes far more practical, even if you are changing just one radiator, to drain the entire system – this will also put fresh clean water into the system.

Step 4

Take your new radiator and take the two end valve and wrap some PTFE tape (also known as Plumbers Tape) around the screw fittings.

Now insert these fittings into the radiator and tighten the nuts fully. Now take the Bleed Nipple and fit this to the radiator at the opposite end. This will generally not require PTFE tape as it comes with a rubber seal. You have now assembled the fittings on the radiator.

Step 5

It is most unlikely that your new radiator will fit onto the old brackets that are on the wall, so you’ll need to remove these and fit new ones. Start by removing the old brackets by unscrewing them with a screwdriver.

Once they are off the wall you can repair the holes with some filler and then sand down to make smooth. To fit the new brackets you need to measure the length of the window sill and the length of radiators – note most radiators are fitted to the window wall, below the window.

The reason for this is so that the radiators in your home do not take up valuable wall space. What you want to achieve here to to center the radiator to the window so that it better blends in and doesn’t look odd or uneven.

Take a pencil and mark the center point, on the wall, of the window. Now mark the center point of the radiator with your pencil. You can now line up these points so that the radiators sit central to the window with the same amount of over-hang or under-hang on the window.

Step 6

Now that you know where your radiator is to be hung you need to measure out the position of the wall brackets and fit these.

From the center mark you made on the radiator, measure outwards to each of the center points on the radiator bracket hinges.

Do this for both ends. Now from the center of bracket hinges measure upwards to the top of radiator. Repeat this to find the points from the bottom of the radiator.

From the center point on the wall mark a straight line down, using a spirit level to ensure it is vertically level. From this center line you can now transfer the measurement of the bracket hinges to the wall.

Now you will have the position of the wall brackets to be fitted. Fit these by placing the brackets in their marked positions, and then mark all the screw holes.

Take a drill and attach the correct size drill bit for the raw plugs or anchor screws and screw fixings and drill each hole to the depth of the raw plug.

You can get the right depth of the raw plug by placing it on the drill bit and then wrap masking tape around the top. When you drill you can stop drilling upon reaching the masking tape.

Take each of the raw plugs and tap them home and flush to the wall using a hammer. Now place your brackets in position and screw them to the wall.

Step 7

Take your new radiator and hang it on the wall brackets and then place a spirit level across the top of the radiator to ensure that it is level.

Now connect the valves at either end of of the radiators. Remember to use PTFE tape on the threads of the nuts to prevent any leaking.

Turn on the water supply and heating system again and open the bleed valve at the top and open ONLY the FLOW VALVE… This is the one that turns the heating on and off to the radiator.

Your radiator will now start filling with water and as it does so it will push the air out of the bleed valve at the top. Keep an eye on this and once water starts to trickle out you can shut the bleed valve. At the other bottom end, turn the ‘RETURN VALVE’ open which will allow water to circulate throughout the entire system.

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  • Find the best heat pump

    This post would be really very helpful for me for the installation of the central heating radiator in my home. Thanks for providing this great information…